|
Detailed Reference Information |
Bond, Z.A., Cohen, A.L., Smith, S.R. and Jenkins, W.J. (2005). Growth and composition of high-Mg calcite in the skeleton of a Bermudian gorgonian (Plexaurella dichotoma): Potential for paleothermometry. Geochemistry Geophysics Geosystems 6. doi: 10.1029/2005GC000911. issn: 1525-2027. |
|
We used a secondary ion mass spectrometry (SIMS) ion microprobe to analyze magnesium-to-calcium (Mg/Ca) and strontium-to-calcium (Sr/Ca) ratios of high-Mg calcite loculi within the skeleton of a shallow water gorgonian, Plexaurella dichotoma, from Bermuda. A cross section of the gorgonian skeleton reveals loculi embedded within proteinaceous gorgonin arranged in concentric rings about the axial core. Viewed in cross section, the loculi are fan-shaped, 10--140 ¿m in diameter, and composed of bundles of needle-shaped crystals that appear to radiate out from a calcification center. Discrete sample spots, each 20 ¿m diameter, were sputtered from successive loculi along a sample track 3 mm long. Over this distance, 25 bands of high-low density gorgonin couplets were encountered, estimated to represent the period 1963 to 1988. Mg/Ca ratios show an overall, positive correlation with annual sea surface temperatures (SSTs) that is strongest in the autumn months (October--December). High-resolution analyses along the growth axes of individual loculi reveal low variability and no trend, consistent with our interpretation of seasonal growth of these calcite inclusions. The sensitivity of Mg/Ca to interannual changes in average autumn temperatures is 0.47 mmol/mol per ¿C. Conversely, interannual variability in calcite Sr/Ca does not follow the interannual variability in SST and may be influenced primarily by growth rate. |
|
|
|
BACKGROUND DATA FILES |
|
|
Abstract |
|
|
|
|
|
Keywords
Biogeosciences, Biomineralization, Paleoceanography, Corals, Paleoceanography, Sea surface temperature, gorgonian, Mg/Ca, Sr/Ca, calcite, SIMS ion microprobe, biomineralization |
|
Journal
Geochemistry Geophysics Geosystems |
|
Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
|
|
|